Roof supports for long wall mining installations

ABSTRACT

A roof support unit for a mineral mining installation of the type comprising a conveyor along which travels a winning machine including an advancing ram which may be set in a first condition to resist rigidly movement of the conveyor towards the support and in a second condition to yieldingly resist such movement, as well as aligning devices positioned on each side of the ram. In consequence, the support unit may be used with ploughs of the sworded and swordless type.

United States Patent Fliiter, deceased et al.

1 1 May 13, 1975 ROOF SUPPORTS FOR LONG WALL MINING INSTALLATIONS Inventors: Manfred Fliiter, deceased, late of Altlunen. Germany, by Hannelore Emmi Floter, administratrix; Franz Beulker, Werne; Lubomir Plevak, Lunen; Kunibert Becker, Werl, all of Germany Gewerkschaft Eisenhutte Westfalia, Westfalia, Germany Filed: July 25, 1973 Appl. No.: 382,600

[73] Assignee:

[30] Foreign Application Priority Data Aug. 1, 1972 Germany 2237798 US. Cl 299/321; 61/45 D Int. Cl. E21c 29/02 Field of Search 299/31, 32, 18,34, 43;

[56] References Cited UNITED STATES PATENTS 3,192,722 7/1965 Hermann et al 61/45 D 3,482,878 12/1969 Floter 299/32 Primary Examiner-Ernest R. Purser Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT 11 Claims, 7 Drawing Figures ROOF SUPPORTS FOR LONG WALL MINING INSTALLATIONS BACKGROUND OF THE INVENTION In long wall mineral mining, a face conveyor extends along side the mineral face and serves as a guide for a mineral winning machine which travels along the conveyor. The roof of the working is supported by a support system comprising a plurality of support units each of which is equipped with one or more props which may be extended hydraulically and set against the roof.

Each support unit may be connected to the conveyor by one or more advancing rams which, when the props have been set as mentioned above, may be extended to advance the conveyor towards the face. Subsequently, following the release of the props, the advancing ram may be retracted so that, with the conveyor used as an anchorage, the support unit is advanced towards the conveyor. Because of major irregularities in the floor or roof, or after a great number of advancing steps, or in the case of inclined workings, the support units may eventually come to depart from their proper alignment which is perpendicular to the length of the conveyor. Unless a device is provided for continuously reorientating the support units, the entire long wall support system has to be re-aligned at intervals of time. This realignment operation is extremely difficult and may only be carried out if winning operations are suspended for a relatively long period of time. Although the conveyor is advanced in small steps to keep pace with the rate at which the face is being removed, it is generally pre ferred to advance the support units in larger steps, this procedure sometimes being essential in order to control the roof. In designing roof support equipment, it is necessary to take into account the type of winning machine with which it is to be used. Thus, when a sworded plough is used, it is necessary to make provision for the conveyor to perform what may be referred to as *breathing" movements. In other words, the conveyor must be able to yield towards the support system as the plough passes along the conveyor. On the other hand, when a swordless plough is used, movement of the conveyor towards the support system must be rigidly resisted.

One known long wall support system is that described in German Patent specification No. 1,147,907. In this known system, each support unit incorporates a hydraulic advancing ram which is attached at one end to the conveyor and at the other to the support unit. Alignment of the support unit as it is advanced up to the conveyor is achieved by an aligning device which consists of a pair of stop faces arranged on the goaf side of the conveyor and projecting perpendicularly thereto. The stop faces co-operate with counter-stops on the forward props of the frames of the support unit in order to restore the support unit to its desired position perpendicular to the conveyor and to its normal spacing from adjacent support units if necessary. This arrangement suffers in particular from the disadvantage that a substantial force must be exerted upon the advancing support in order to bring about cooperation of the stops and counterstops during a relatively large part of the retraction stroke of the advancing ram. German Patent specification No. l,l36,960 proposes the coupling together of two frames through a parallel guidance and shifting device to form a support assembly. The frames are connected with the said device by way of springs to allow for yieldable movement in the direction transversely of the direction of advance. The said device may have associated with it a guide rod which is connected with the conveyor and guided for displacement in the direction of advance. A compression spring may be interposed between the support and conveyor to force the conveyor against the mineral face with a pressure which is adequate but which permits the conveyor to breathe, that is to yield towards the support system as the winning machine passes by.

A disadvantage of these two known systems is that each is intended for use with a specific type of winning machine, that is, the former system rigidly resists movement of the conveyor away from the face and is therefore suited for use only with a swordless plough while the latter system inherently provides for yielding or breathing of the conveyor so that it is suited for use only with the sworded type of plough, especially a breaker hook plough.

The principle object of the present invention is to avoid the problems of these prior art systems and to provide apparatus for advancing and aligning a support unit which is suitable for use with either type of winning machine described, that is to say it can be arranged to permit yielding of the conveyor when the winning machine is a sworded plough or it can be arranged to block movement of the conveyor when it is used with a swordless plough.

SUMMARY OF THE INVENTION The invention provides two preferred embodiments, each of which includes an aligning device interposed between the support unit and the conveyor and arranged one on each side of an advancing ram which is extensible to advance the conveyor and retractable to advance the support unit. Although in the following description and claims reference is made for convenience to the advancing ram in the singular it will be understood by those skilled in the art that it falls within the scope of the invention for several rams to be arranged one beside the other. Broadly stated, means is provided in each embodiment to allow the ram to be set in either of two conditions when it has been retracted, namely a first condition in which the ram rigidly resists or blocks movement of the conveyor away from the face and a second condition in which the ram permits yielding or breathing of the conveyor. The ram may be set in the first condition by maintaining the ram in the main pressure line or by isolating the ram. The second condition in which the ram may yield may be achieved by discontinuing retraction of the ram before the piston has reached its end position and connecting the chamber behind the piston to a suitable expansible volume of fluid. Thus, the ram may be connected to a pressure reservoir or accumulator of the type having a diaphragm or piston which is acted upon by a compression spring. The volume of the reservoir may increase by a predetermined amount which determines the distance through which the ram is capable of yielding. This distance is of course arranged to be equal to the distance through which the conveyor should move during breathing.

Positioned on each side of the advancing ram an aligning device which is in the form of a stop of adjustable effective length. That is to say, when the advancing ram has been retracted and the conveyor is to be allowed to breathe, these stops do not hinder such breathing movement but when the conveyor is to be held unyieldingly, the stops are capable of forming, in effect, rigid struts between the support and the conveyor.

In one embodiment, each aligning device comprises a bell-crank lever with arms of unequal length pivoted to a mounting bracket on the goaf-side side-section of the conveyor or a part attached thereto. Each lever may be pivoted into a first position in which its longer arm extends perpendicularly to the conveyor and can abut against a suitable stop surface on the support unit. Alternatively, the bell-crank levers can be pivoted into a second position in which the longer arms extend obliquely relative to the conveyor so that their effective length is reduced. The shorter arms of the levers may be connected to the ends of a cross head on the advancing ram. During the advance of the support unit, the levers are pivoted into the first mentioned position and hence the position of the ram relative to the conveyor at the end of its retraction stroke determined the final position of the bell-crank levers and therefore the effective length of the longer arm. In other words, if the ram is maintained in its fully retracted condition the bell-crank levers remain in their first position in which the ends of the longer arms abut upon the stop surface and movement of the conveyor is rigidly resisted as is appropriate when a swordless plough is to be used. If, however, after the ram has been fully retracted it is extended by a small amount, the levers pivot out of the above-mentioned first positions into their second positions in which the longer arms extend obliquely of the conveyor and their distal ends are spaced from the support.

The ram has now been given a capacity for further retraction which the stops are not effective to prevent. Assuming that a sworded plough is to be used, the chamber behind the piston of the ram may be connected with the elastic pressure reservoir so that although force is applied to it the conveyor is allowed to yield. The distance between the levers and the support and the reserve stroke of the ram is arranged to equal the permissible breathing distance of the conveyor.

The cross head which interconnects the two bellcrank leves is preferably provided with a surface intended to engage the side of the conveyor or a part attached thereto. The pivot connection between each bell-crank lever and the cross head may be formed by means of a pin or journal on the shorter arm and engaging in a slot in the cross head.

In accordance with the second embodiment of the invention, each aligning device is in the form ofa piston and cylinder unit disposed on a respective side of the advancing ram at the forward end of the support unit. The piston rods of these rams project forwardly in the manner of plungers and co-operate with the side section of the conveyor or a part carried thereby. Alternatively, of course, the pistons of the said units may be rigid with the support and the cylinders project forwardly. To permit breathing of the conveyor, for use with a sworded plough, the aligning cylinders are connectable (preferably together with the advancing ram) with the reservoir or accumulator of the type described above through the intermediary of a suitable control valve. When the support is to be used with a swordless winning machine, the aligning cylinders can be isolated hydraulically so that the conveyor is rigidly supported against the support unit.

The apparatus provided by the invention makes it possible depending upon the type of winning machine which is being used to resist movement of the conveyor towards the support system either rigidly, as is necessary when a swordless plough is used, or yieldingly, as is necessary when a sworded plough is used, the advancing ram being connected in this latter case with a suitable elastic pressure reservoir, the pressure of which suffices to hold the conveyor with appropriate force against the mineral face but which on the other hand is such as to allow breathing movement of the conveyor during passage of the winning machine. These two modes of operation are particularly facilitated by the aligning device provided by the invention, in that the effective length of the latter is variable whereby a rigid or resilient support of the conveyor is achieved. In addition, the support unit can be positioned exactly perpendicular to the conveyeor during the advance of the support unit under the action of the advancing cylinder through the intermediary of the aligning devices with relatively low expenditure of power.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates in plan view part of a conveyor and a roof support unit according to a first embodiment of the invention, intended for use with a swordless plough, and depicted following the advance of the support unit;

FIG. 2 is a view similar to FIG. 1 but showing the support unit at the end of its advance, when intended for use with a sworded plough,

FIG. 3 is a view corresponding to FIG. 1 but of a second embodiment;

FIG. 4 is a view corresponding to FIG. 2 but of the second embodiment;

FIGS. 5 to 7 illustrate the steps performed in bringing the first embodiment into the position shown in FIG. 2.

DESCRIPTION OF FIRST PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a mining installation includes an armoured face conveyor 2 and a series of advancing roof support units 1, only one of which is shown, disposed on the goaf side of the conveyor. Each of the supports 1 has a base to which a double acting ram 3 is pivoted about a horizontal axis. The ram 3 serves to advance the conveyor when the props 15 are set against the roof and thereafter to advance the support by pulling it up to the conveyor after the props have been temporarily lowered. The ram acts on the conveyor by way of a linkage which includes a cross head 9 pivoted about a vertical axis to the end of the ram and a pair of bell crank levers 4 each having arms 7 and 8 of unequal length. The levers 4 have vertical pivot axes and are supported one on each side of the ram 3 by respective support brackets 5 mounted upon the goaf-side side-section of the conveyor. The cross head 9 is articulated at its ends to the shorter arms 7 of the levers 4.

Each of the brackets 5 has a pair of stop faces 10 and 11 which co-operate with the arms 7 and 8 to determine the end positions of the levers, the arm 8 of each lever coming into contact with the associated stop face 11 when that arm extends perpendicularly to the length of the conveyor. The other stop face 10 engages the shorter lever arm 7 when the longer arm extends obliquely of the conveyor and has an effective length which is less by a distance x than its effective length when the longer arm extends perpendicularly of the conveyor. Be effective length is meant the distance between the pivot axis on the lever 8 and the extremity of the lever arm measured in the horizontal direction perpendicularly to the conveyor. The length of each of the shorter lever arms 7 and its angular relationship with the associated longer lever arm is such that the cross-head can be positioned at a distance from the conveyor corresponding to the said distance x. In operation, the support unit is initially close behind the conveyor and is anchored in position by its props which are set against the roof. As work progresses, the face recedes and the conveyor is advanced in small steps to keep pace with it by extending the ram 3. When the conveyor is being advanced in this way, the face 14 of the cross head 9 acts directly upon the side section 6 of the conveyor so that the levers 4 are in the position shown in FIG. 2. Eventually, the ram becomes extended to its full stroke, as depicted in FIG. 5, so that the support must be advanced to the position shown in chain lines. This movement is achieved by releasing the props and retracting the ram 3. The conveyor serves as an anchorage for the support which is in consequence drawn across the floor up to it. Since tension is now applied to the linkage connecting the ram to the conveyor, the levers 4 swing into the position shown in FIG. 6 with the longer arms 8 in contact with the stop faces 11. The arms 8 therefore make contact with the end face 16 of the base of the support and prevent further movement of the support towards the conveyor. The provision of two levers 4 one on each side of the ram 3 ensures that the support is properly positioned perpendicularly to the conveyor 2 at the end of its advance. If the mining installation is making use of a swordless type of plough in which movement of the conveyor away from the face during passage of the plough must be rigidly resisted, the linkage is maintained in this position and the ram 3 isolated or maintained in connection with the main pressure line, and the props extended. If, however, a sworded plough is in use, after the props of the support have been reset against the roof, the ram 3 is extended so that the position shown in FIGS. 2 and 7 are obtained in which the effective lengths of the arms 8 have been reduced by the distance x which corresponds to the permitted amount of breathing or yielding movement of the conveyor. This extension of the ram provides it with a reserve stroke R which is equal to the distance x. The ram 3 is then connected by means ofa valve 17 with an elastic pressure reservoir (not shown) so that the advancing ram can yield through the range of this reserve stroke. It follows that although the conveyor is urged forward with an adequate force against the mineral face it can be pushed back as the winning machine passes through the distance x.

DESCRIPTION OF SECOND PREFERRED EMBODIMENT Referring now to FIGS. 3 and 4, the support unit 1, conveyor 2 and advancing ram 3 are essentially similar to the corresponding components shown in FIGS. 2 and 2 but the aligning system in this embodiment is constituted by a pair of hydraulic cylinders 18 which are disposed at the forward end of the base of the support unit, one on each side of the ram 3. Each cylinder houses a piston, the rod 19 of which extends from the cylinder in the manner of a plunger and is arranged to bear against the goaf-side side-section 6 of the conveyor so as to position the support unit perpendicularly to the length of the conveyor during the final stage of the advance performed by the support. The aligning cylinders 18 are pressurised to the same extent as the advancing ram 3 at least until the end of the advance of the support which, as before, takes place with the props 15 lowered. Since the effective area of the pistons of the aligning cylinders is at least twice as great as that of the piston of the advancing. ram, the latter still has a reserve stroke R corresponding to the distance x permitted for breathing of the conveyor after the termination of the movement of the support (FIG. 3).

If the installation is utilising a sworded plough, after the support has been brought up to the conveyor, provision for breathing is made by connecting the advancing ram and the aligning cylinders with an elastic pres sure reservoir. As a result, the armoured conveyor is allowed to yield as represented in FIG. 4 towards the support system through the permitted breathing distance x under the pressure of the winning machine.

If, however, a swordless winning machine is in use, so that the conveyor must be supported rigidly by the support system, the aligning cylinders and the rams 3 are isolated by the valve 20 so that they retain the position illustrated in FIG. 3 at the end of the support advance operation and during the passage of the winning machine.

What we claim is:

1. In a winning installation comprising a conveyor and a mineral winning machine guided for movement thereon, a long wall support system including at least one support unit comprising a frame, an advancing ram mounted to said frame, and means connecting said ram and said conveyor, said means comprising a cross head on said ram, a pair of bell-crank levers, support means carried by said conveyor and pivotally mounting said bell-crank levers one on each side of said ram, each of said bell-crank levers having a first arm anticulated to said cross head and a second arm forming an adjustable stop for said support unit extending between said unit gind conveyor and being pivotable between a position extending obliquely of the length of the conveyor and a position extending normally of the length of the conveyor.

2. In a mineral mining installation comprising a conveyor and a mineral winning machine guided for movement thereon, a longwall support system including at least one support unit comprising a frame, an advancing ram mounted to said frame, means for directing pressure fluid to said ram to extend the ram and advance the conveyor and for directing pressure fluid to the ram to retract the ram and advance the support unit, plunger means disposed one on each side of the advancing ram and adapted to bear on the conveyor, an elastic pressure reservoir, and control means selectively operable to isolate said ram from said pressure fluid so that said support unit substantially rigidly resists movement of said conveyor towards said unit and to connect said ram to said pressure reservoir so that movement of said conveyor towards said unit is yieldingly resisted within the limits determined by the stroke of said plunger means.

3. In a mining installation comprising a conveyor, a mineral winning machine guided for movement on said conveyor and a source of pressure fluid, a longwall support system comprising a plurality of support units each connected with the conveyor by pressure fluid operated advancing ram which is extensible to advance said conveyor and retractable to advance said support unit, at least one support unit having an advancing ram which when retracted is adapted to be placed in either of two conditions, namely a first condition in which it forms a substantially rigid connection between the support unit and conveyor and a second condition in which it yieldingly resists movement of the conveyor towards said support unit, and aligning devices each formed by stops of adjustable effective length, whereby the advancing ram and aligning devices may be arranged selectively to block and to render possible breathing movement of the conveyor towards the support system.

4. A support system as claimed in claim 3, wherein the advancing ram in the fully retracted condition has available a reserve stroke which corresponds to the maximum permissble breathing movement of the conveyor, a spring-loaded elastic pressure reservoir, and valve means for selectively connecting said advancing ram to either of said pressure source and reservior, or for isolating said ram.

5. A support system as claimed in claim 3, wherein support brackets are provided on the conveyor and each aligning device comprises a bell-crank lever having two lever arms of unequal length, each lever being pivoted to a respective support bracket, and a cross head articulated to the shorter arms of the said levers, said advancing ram being connected to said cross head centrally between said bell crank levers, said support brackets having stop faces determining end positionsof said bell-crank levers.

6. A support system as claimed in claim 5, wherein the longer arm of each lever has first and second terminal positions, and the effective length of said arm reduces during movement from said first position to siad second position by a distance equal to the permissible breathing distance.

7. A support system as claimed in claim 6, wherein the cross head is provided with an abutment face for direct abutment on the conveyor goaf-side side-section.

8. A support system as claimed in claim 5, wherein the frame of said support unit is provided with a stop member on which the free ends of the longer lever arms abut.

9. A support system as claimed in claim 3, wherein each aligning device comprises a piston and cylinder unit disposed symmetrically on a respective opposite side of the advancing ram, said units having piston rods which serve as plungers and cooperate with the goafside side-section of the conveyor.

10. A long wall support system as claimed in claim 9, wherein said aligning cylinders have a stroke which is at least equal to the maximum permissible breathing movement of the conveyor.

11. A longwall support system as claimed in claim 9, including a spring loaded, elastic, pressure reservior and valve means for connecting the piston and cylinder units and the advancing ram simultaneously with said 

1. In a winning installation comprising a conveyor and a mineral winning machine guided for movement thereon, a long wall support system including at least one support unit comprising a frame, an advancing ram mounted to said frame, anD means connecting said ram and said conveyor, said means comprising a cross head on said ram, a pair of bell-crank levers, support means carried by said conveyor and pivotally mounting said bell-crank levers one on each side of said ram, each of said bell-crank levers having a first arm anticulated to said cross head and a second arm forming an adjustable stop for said support unit extending between said unit and conveyor and being pivotable between a position extending obliquely of the length of the conveyor and a position extending normally of the length of the conveyor.
 2. In a mineral mining installation comprising a conveyor and a mineral winning machine guided for movement thereon, a longwall support system including at least one support unit comprising a frame, an advancing ram mounted to said frame, means for directing pressure fluid to said ram to extend the ram and advance the conveyor and for directing pressure fluid to the ram to retract the ram and advance the support unit, plunger means disposed one on each side of the advancing ram and adapted to bear on the conveyor, an elastic pressure reservoir, and control means selectively operable to isolate said ram from said pressure fluid so that said support unit substantially rigidly resists movement of said conveyor towards said unit and to connect said ram to said pressure reservoir so that movement of said conveyor towards said unit is yieldingly resisted within the limits determined by the stroke of said plunger means.
 3. In a mining installation comprising a conveyor, a mineral winning machine guided for movement on said conveyor and a source of pressure fluid, a longwall support system comprising a plurality of support units each connected with the conveyor by pressure fluid operated advancing ram which is extensible to advance said conveyor and retractable to advance said support unit, at least one support unit having an advancing ram which when retracted is adapted to be placed in either of two conditions, namely a first condition in which it forms a substantially rigid connection between the support unit and conveyor and a second condition in which it yieldingly resists movement of the conveyor towards said support unit, and aligning devices each formed by stops of adjustable effective length, whereby the advancing ram and aligning devices may be arranged selectively to block and to render possible breathing movement of the conveyor towards the support system.
 4. A support system as claimed in claim 3, wherein the advancing ram in the fully retracted condition has available a reserve stroke which corresponds to the maximum permissble breathing movement of the conveyor, a spring-loaded elastic pressure reservoir, and valve means for selectively connecting said advancing ram to either of said pressure source and reservior, or for isolating said ram.
 5. A support system as claimed in claim 3, wherein support brackets are provided on the conveyor and each aligning device comprises a bell-crank lever having two lever arms of unequal length, each lever being pivoted to a respective support bracket, and a cross head articulated to the shorter arms of the said levers, said advancing ram being connected to said cross head centrally between said bell crank levers, said support brackets having stop faces determining end positions of said bell-crank levers.
 6. A support system as claimed in claim 5, wherein the longer arm of each lever has first and second terminal positions, and the effective length of said arm reduces during movement from said first position to siad second position by a distance equal to the permissible breathing distance.
 7. A support system as claimed in claim 6, wherein the cross head is provided with an abutment face for direct abutment on the conveyor goaf-side side-section.
 8. A support system as claimed in claim 5, wherein the frame of said support unit is provided with a stop member on which the free ends of the longer lever arms abut.
 9. A support system as clAimed in claim 3, wherein each aligning device comprises a piston and cylinder unit disposed symmetrically on a respective opposite side of the advancing ram, said units having piston rods which serve as plungers and cooperate with the goaf-side side-section of the conveyor.
 10. A long wall support system as claimed in claim 9, wherein said aligning cylinders have a stroke which is at least equal to the maximum permissible breathing movement of the conveyor.
 11. A longwall support system as claimed in claim 9, including a spring loaded, elastic, pressure reservior and valve means for connecting the piston and cylinder units and the advancing ram simultaneously with said reservoir. 